1. Field of the Invention
The present invention relates generally to a non-aqueous electrolyte secondary battery provided with a positive electrode, a negative electrode using carbon material as a negative electrode active material, and a non-aqueous electrolyte solution, and particularly, to a non-aqueous electrolyte secondary battery using carbon material as a negative electrode active material, which is featuring an increased cycle life and an improved output characteristics at high rate.
2. Description of the Related Art
Recently, as one of advanced batteries featuring high power and high energy density, non-aqueous electrolyte secondary batteries of high electromotive force derived from oxidation and reduction of lithium, using a non-aqueous electrolyte solution, have come into practical use.
In such non-aqueous electrolyte secondary batteries, carbon materials capable of absorbing and desorbing lithium ions including graphite and cokes are generally used as a negative electrode active material in a negative electrode. Especially, where graphite-containing carbon material having high crystallinity is used, the non-aqueous electrolyte secondary batteries having high energy density are attained, therefore, the graphite-containing carbon material has come into wide use.
There has been proposed to use the non-aqueous electrolyte solution containing a vinylene carbonate derivative, to increase cycle life of the non-aqueous electrolyte secondary battery using the graphite-containing carbon material as the negative electrode active material (see Japanese Patent Publication No. 8-45545).
Where the non-aqueous electrolyte solution containing the vinylene carbonate derivative is used in the non-aqueous electrolyte secondary battery using the graphite-containing carbon material as the negative electrode active material, the vinylene carbonate derivative is reduced during a first charge, a surface film is formed on a surface of the negative electrode active material, thus, side reactions in which the non-aqueous electrolyte solution is decomposed during charge and discharge are prevented for the effect of the surface film, as a result, the cycle life of the non-aqueous electrolyte secondary battery is expected to increase.
Unfortunately, however, where the surface film is formed on the surface of the negative electrode active material, there have remained problems that output characteristics during discharge at high current is degraded by the surface film, especially, in middle or large sized non-aqueous electrolyte secondary batteries of high output, the output characteristics at high current is extremely degraded.